Do you mean Google Chrome vs Chromium, or the stable, beta, etc. versions of Chrome?
Unless you enjoy beta testing or are a developer working on stuff for the browser, I suggest google-chrome-stable.
For the welcome box, try closing it, then opening a terminal and typing in "mintwelcome".
This should open the welcome box. When you make this one freeze you should get output on the terminal which gives more info about the problem.
PC: LMDE x64 MATE/Cinnamon, Kernel 3.9, Nvidia GT620, i7 3770K, 16GB RAM
Laptop: LMDE x64 MATE, Kernel 3.8.6, i3, 6GB RAM